import { Q, M, D } from '../../constant'
export default (function (o, c) {
  var proto = c.prototype

  proto.quarter = function (quarter) {
    if (!this.$utils().u(quarter)) {
      return this.month((this.month() % 3) + (quarter - 1) * 3)
    }

    return Math.ceil((this.month() + 1) / 3)
  }

  var oldAdd = proto.add

  proto.add = function (number, units) {
    number = Number(number) // eslint-disable-line no-param-reassign

    var unit = this.$utils().p(units)

    if (unit === Q) {
      return this.add(number * 3, M)
    }

    return oldAdd.bind(this)(number, units)
  }

  var oldStartOf = proto.startOf

  proto.startOf = function (units, startOf) {
    var utils = this.$utils()
    var isStartOf = !utils.u(startOf) ? startOf : true
    var unit = utils.p(units)

    if (unit === Q) {
      var quarter = this.quarter() - 1
      return isStartOf
        ? this.month(quarter * 3)
            .startOf(M)
            .startOf(D)
        : this.month(quarter * 3 + 2)
            .endOf(M)
            .endOf(D)
    }

    return oldStartOf.bind(this)(units, startOf)
  }
})
